This is one of the dumbest things I've ever read. The “what if" argument can be applied to anything and doesn't prove anything. As far as we know, Dabuz is the best RosaLuma player. He gets better results than every other Rosa player. Therefore, his style of play can be assumed to be the most optimal until proven otherwise.
All of this is great and all, but since when were you the Rosalina aficionadao? Your opinion of how Rosa should be played is just that, an opinion. Unless you have the results to back it up, your statements are all wishful thinking. The thing that makes Rosa so annoying is her defensive play and using Luma as a shield. If you try to play aggressive with her, you're just a giant hotbox running at your opponent to get hit over and over. Your simile to Shull is not true at all. Playing Rosa defensively is very effective, while playing Shulk with one momado art is not.
Results aren't the end-all, be-all of what defines what a character is. Don't you know that tier lists don't even use results as the sole factor in their formation? Character potential is another big one. And there is a lot of untapped potential in Rosalina on Dabuz's part at the VERY least, and in many other players/characters. Stop talking as if the meta is static.
That second paragraph just tells me you don't know how to play the character, at all.
Okay, so saying Dabuz plays Rosalina optimally was very hasty for me to say, as nobody plays any of their characters to their fullest potential because nobody really knows any character's full potential yet. However, I still think that looking up to Dabuz as a role model for how to play Rosalina well is not a bad decision. The way I've always gotten better at a competitive game was by looking up how the pros played and taking tips from them. It's not a bad idea.
Now I wanna ask you a couple questions. I'm assuming you play Rosalina the way you describe, which you believe to be optimal(or at least close to it), correct? If so, then could you direct me to any tournaments or matches where you have won playing Rosalina this way? Tournament results establish a lot of credibility in a player. Also, could you explain to me how the Japanese or European Smash 4 scene is more varied than America's? Provide examples? I want definitive proof that Japan or Europe actually use a wider variety of characters than America does.
I never said he can't be used as a reference at all. The problem lies in using him as the end-all, be-all reference. Since he only uses one particular playstyle for Rosalina rather than mastering all of them to play her as a paradigm shifter, he inherently limits himself, especially when other players with other playstyles (falln plays a very aggressive Rosalina for example, and AceStarthe3rd plays a very balanced, all-round Rosalina) have proven other playstyles to be valid and fill in gaps in Dabuz's playstyle - ergo, the OPTIMAL way to play Rosalina is as a paradigm shifter, by switching up your playstyle for Rosalina AND Luma according to the situation. Essentially, it's OK to use him as a reference to a point, or if you PERSONALLY only want to play Rosalina defensively, but exclusively focusing on Dabuz as a reference for "how Rosalina plays" does not teach you how to play as Rosalina, it teaches you how to be play as Dabuz. Same goes with any other top player. You have to observe a variety of them, and try to innovate your own playstyle elements too.
For one example of a flaw in Dabuz's playstyle, he RARELY sends Luma out (which is likely a side effect of him not understanding Luma's untethered controls fully - a lot of players don't). Another example, he never really attacks unless he's sure Rosalina can come out unscathed. I have a video example of myself benefiting from sending my Luma out and INTENTIONALY letting Rosalina get hit (as there are benefits to it, such as letting Luma get in easy punishes that can KO or lead to one, or starting the "Luma Spin" technique, which can only be started while Rosalina is in hit stun).
I don't play in tournaments, but I have had sessions with tournament players in my country, and have been recommended to compete in various tournaments, including
Celtic Throwdown, which is the biggest Irish gaming tournament that even has Nintendo as a sponsor. I hope to compete in it and a few other tournaments here, but unfortunately my life situation cannot accommodate this for now (and I know many other talented players suffer from this restriction). I also tend to get friend requests from For Glory players (talented ones) after having really nice sessions with them. I've also had people come to me for advice on Rosalina an awful lot, or request to spar with me. I may not be the best player in the world yet, but I am confident I have an expansive knowledge on the character and feel I have been pushing her forward and I have discovered things before others.
As far as European characters go, I believe Bowser, Fox, and R.O.B are of the more popular variety here compared to the US (all characters with playstyles that vary between them), off the top of my head. You can always just go look up a variety of tournaments statistics yourself, though, if you really are curious.